ActiveRecordRelations support for generic definitions in AR models

lib/tapioca/dsl/compilers/active_record_relations.rb

@@ -278,7 +278,16 @@ def common_relation_methods_module
 
         sig { returns(String) }
         def constant_name
-          @constant_name ||= T.let(T.must(qualified_name_of(constant)), T.nilable(String))
+          @constant_name ||= T.let(constant_name_of(constant), T.nilable(String))
+        end
+
+        sig { params(constant: ConstantType).returns(String) }
+        def constant_name_of(constant)
+          if T::Generic === constant
+            generic_name_of(constant)
+          else
+            T.must(qualified_name_of(constant))
+          end
         end
 
         sig { params(method_name: Symbol).returns(T::Boolean) }

lib/tapioca/helpers/rbi_helper.rb

@@ -138,5 +138,33 @@ def valid_parameter_name?(name)
     rescue SyntaxError
       false
     end
+
+    sig { params(constant: T.all(Module, T::Generic)).returns(String) }
+    def generic_name_of(constant)
+      type_name = T.must(qualified_name_of(constant))
+      return type_name if type_name =~ /\[.*\]$/
+
+      type_variables = Runtime::GenericTypeRegistry.lookup_type_variables(constant)
+      return type_name unless type_variables
+
+      type_variables = type_variables.reject(&:fixed?)
+      return type_name if type_variables.empty?
+
+      type_variable_names = type_variables.map { "T.untyped" }.join(", ")
+
+      "#{type_name}[#{type_variable_names}]"
+    end
+
+    sig { params(constant: Module).returns(T.nilable(String)) }
+    def qualified_name_of(constant)
+      name = name_of(constant)
+      return if name.nil?
+
+      if name.start_with?("::")
+        name
+      else
+        "::#{name}"
+      end
+    end
   end
 end